1. Field of the Invention
The present invention relates to a tape drive device which is suitably usable for a tape cassette serving as a recording medium used for data storage, etc.
2. Description of the Related Art
A so-called tape streaming drive has been known as a drive device which is able to record/reproduce digital data in a magnetic tape. Such a tape streaming drive can have an extremely large recording capacity, for example, of about several tens to several hundreds gigabytes although its capacity is dependent on the tape length of a tape cassette serving as a recording medium. Therefore, the tape streaming device has been widely used in various fields, for example, to back up data recorded in a medium such as a hard disc of the main body of a computer. Further, it is also suitably used to store image data or other data having a large data size.
As the above tape streaming drive has been proposed one which uses a 8-mm VTR tape cassette as a recording medium and utilizes a helical scan system based on a rotational head to record/reproduce data.
The tape streaming drive proposed is designed so that a user can form partitions of desired number and capacity on a magnetic tape of a tape cassette by initializing the magnetic tape of the tape cassette. Accordingly, user data can be recorded into a data area formed every partition and user data thus recorded can be reproduced from a data area formed every partition.
In order to perform a proper recording/reproducing operation on a magnetic tape of a tape cassette in a data storage system comprising a tape streaming drive and a tape cassette as described above, various position information on the magnetic tape and information on the use record of the magnetic tape, etc. are required as management information which is used to manage the recording/reproducing operation, etc. by the tape streaming drive.
Therefore, it is considered that an area for the management information as described above is provided at the head position of the magnetic tape or it is individually provided at the head position of each partition formed on the magnetic tape.
At the tape streaming drive side, various processing operations are carried out so that the area of the management information is accessed to read out desired management information before the data recording or reproducing operation is carried out on the magnetic tape and the subsequent recording/reproducing operation is properly carried out on the basis of the management information.
After the data recording or reproducing operation is completed, in order to rewrite the content of the management information which is required to be altered due to the execution of the recording/reproducing operation, the area for the management information is accessed again to rewrite the content of the information and then the processing waits for a next recording/reproducing operation. Thereafter, the tape cassette is unloaded and ejected by the tape streaming drive.
However, when the recording/reproducing operation is carried out on the basis of the management information described above, the tape streaming drive is required to access the management information area at the head of the magnetic tape or the head of the partition at the start time when each of the recording and reproducing operations is carried out and also access the management information area again at the end time when the operation is completed to perform data writing/reading operation. That is, it is impossible to perform the loading or unloading operation of the tape at some midpoint on the magnetic tape at which the data recording/reproducing is completed.
In the case of the tape streaming drive, the magnetic tape must be physically fed for access and thus it takes a long time to access the management information area at the head of the magnetic tape or at the head of the partition when the recording/reproducing operation is completed. Particularly, when the data recording/reproducing operation is completed at a position on the magnetic tape which is physically far away from the management information area on the magnetic tape, the magnetic tape must be fed by the amount corresponding to the distance between the operation-completed position and the management information area, and thus it needs extra time.
As described above, in a data storage system using a tape cassette as a medium, a relatively long time is needed to complete one recording/reproducing operation, that is, to perform a series of access operations to be carried out from the time when the loading of the magnetic tape is started until the time when the unloading of the magnetic tape is finally finished. However, it is preferable to reduce the time required for the series of access operations as much as possible.
In view of the foregoing situation, there has been developed such a technique that a non-volatile memory or the like is provided in the housing of a tape cassette and management information is stored in the non-volatile memory. A tape streaming drive supporting such a tape cassette is provided with an interface for writing/reading data into/from the non-volatile memory, and reads/writes the management information on the data recording/reproducing operation for the magnetic tape from/into the non-volatile memory. With this construction, it is unnecessary to rewind the magnetic tape to the tape top position thereof when the magnetic tape is loaded/unloaded, and thus the loading/unloading operation of the magnetic tape can be performed at any position even when the magnetic tape is located at some midpoint.
In the present situation, from the viewpoint of the above technical background of the related art, there is required a tape streaming drive having a compatible function which supports both of a tape cassette type having a non-volatile memory and a tape cassette type having no non-volatile memory.
For the tape streaming drive having the compatible function as described above, it is preferable from the viewpoint of reliability that its functionality as equipment is enhanced as much as possible on the assumption that it has the compatible function.
For example, with respect to the tape cassette having the non-volatile memory (hereinafter merely referred to as xe2x80x9cmemoryxe2x80x9d), it must be taken into consideration that there may occur such a situation that it is impossible to read data from the memory due to failure of the connection point of the memory or the like. In addition, the tape streaming drive is also required to smoothly perform the recording/reproducing operation on the magnetic tape even when the above situation occurs.
The present invention has been implemented in view of the foregoing problems, and has an object to enhance reliability and functionality as equipment in a tape streaming drive having a compatible function for both of a tape cassette having a non-volatile memory and a tape cassette having no non-volatile memory.
Therefore, according to a first aspect of the present invention, there is provided a recording medium in which a magnetic tape is accommodated in a tape cassette, characterized in that the magnetic tape has a management information area in which desired management information to manage the recording/reproducing operation on the magnetic tape is recorded, and the tape cassette is provided with a memory for storing management information having the information content corresponding to management information recorded in the management information area, wherein the management information area contains an area for recording management information location identifying information which indicates the location of preferential management information which should be preferentially referred to by a tape drive device for performing a recording/reproducing operation in conformity with the tape cassette.
According to a second aspect of the present invention, there is provided a tape drive device which performs a recording/reproducing operation in conformity with a tape cassette with a magnetic tape having a management information area in which management information to manage the recording/reproducing operation on the magnetic tape is recorded, characterized by comprising: tape drive means for recording or reproducing information on or from a magnetic tape of a loaded tape cassette; memory drive means for reading out from or writing into a memory management information having the information content common to management information to be recorded in the management information area on the loaded tape cassette when the management information concerned is recorded in the memory; detection means for detecting management information location identifying information indicating the location of preferential management information to be preferentially referred to by the tape drive device from the management information read out from the magnetic tape by the tape drive means; and control means for identifying the location of the preferential management information on the basis of the management information location identifying information detected by the detection means and controlling the memory drive means so that when it is identified that the preferential management information exists in the memory, a reading trial operation of the management information stored in the memory is carried out, wherein when it is impossible to read out the management information from the memory as a result of the reading trial operation of the management information, the control means controls the tape drive means so as to write into a management information recording area of the magnetic tape the management information location identifying information indicating that the preferential management information exists in the management information recording area on the magnetic tape.
According to each of the recording medium and the tape drive device thus constructed, when a tape cassette which may be provided with a memory having management information stored therein is loaded, on the basis of the management information location identifying information set as one management information in the magnetic tape, the tape drive device can identify whether one of the magnetic tape and the memory should be selected as a location of the management information to be preferentially used.
In addition, in a case where it is identified on the basis of the management information location identifying information read out from the magnetic tape that the management information to be preferentially used is located in the memory, if it is impossible to read out the management information from the memory due to some cause, the content of the management information location identifying information is rewritten to indicate that the management information to be preferentially used is located in the magnetic tape. Through this operation, the tape cassette is allowed to be subsequently handled as a tape cassette having no memory on the system.
Further, in a case where it is identified on the basis of the management information location identifying information read out from the magnetic tape that the management information to be preferentially used is located in the magnetic tape, the tape drive device is enabled to subsequently perform a recording/reproducing operation which is conformable to a tape cassette having no memory.